1. Field of the Invention
The present invention is related to an energy-efficient touch panel device and related method, and more particularly, to a touch panel device and related method which can consume less power and have a long standby time.
2. Description of the Prior Art
For years, most IT products utilized traditional ways like keyboards or mouse as the standard user interfaces. After the touch panel devices emerged as a new type of user interface, people start to enjoy it as a very convenient way to input command by selecting objects on the screen. On the other hand, as the concept of environmental protection draws more and more attention, and as new generations of IT products appear on the market, the concepts of “green product” gradually influence all design and manufacturing works of the IT products, which include the touch panel device. Besides that, saving power consumption can have other benefits, too; for example, the standby time of the IT product can be extended, and the users need not to charge the battery of the device very often, so the users' convenience can be advanced.
The touch panel and related control device are mostly seen in the portable IT products. Please refer to FIG. 1. FIG. 1 illustrates a schematic diagram of a touch panel PANEL1 and a control device 12 according to the prior art. The touch panel PANEL1 usually includes many traces in the horizontal direction (X trace) and vertical direction (Y trace), for forming the touch panel functions on the touch panel; these traces are used for sensing the human body's capacitance in order to generate analog output voltages. Meanwhile, according to the operating principles of the touch panel, different traces correspond to different capacitive load parameters.
When a touch event happens to the touch panel PANEL1, the analog output voltages of some horizontal traces as well as some vertical traces may change according to where the touch event happened, and the control device 12 can detect the touch event by monitoring the analog output voltage of each trace. Inside FIG. 1, connected to the touch panel PANEL1, there is a control device 12, which includes an analog to digital converter 120, an operating control unit 122 and a host interface unit 124. The analog to digital converter 120, directly connected to the touch panel PANEL1, is used for converting the analog output voltages into some data in digital format, and the resulting digital data is then transferred to the operating control unit 122. The operating control unit 122 performs specific algorithms to process the data to judge whether there exists a touch event. When the operating control unit 122 confirms a touch event, the host interface unit 124 will output a message to a computer host HOST1 to notify the happening of the touch event. Noticeably, since different traces in the touch panel have different capacitive load parameters, every time the analog to digital converter 120 converts an analog output voltage, the analog to digital converter 120 needs to regulate its transfer ratio (magnitude of amplification) based on the capacitive load parameter of the corresponding trace, such that the influence of different capacitive load corresponding to different trace can be erased (normalized). By this way, the digital data output by the analog to digital converter 120 can be normalized by the analog to digital converter 120, and the operating control unit 122 can perform data operations based on those normalized data.
Noticeably, inside the control device 12, between the operating control unit 122 and the analog to digital converter 120, the capacitive load parameters, used for regulating the transfer ratio of the analog to digital converter, are supplied by the operating control unit 122 once at a time. In other words, every time the analog to digital converter 120 performs a conversion, only one corresponding capacitive load parameter is transferred from the operating control unit 122 to “update” the transfer ratio of the analog to digital converter 120. Meanwhile, right after each analog to digital conversion, the digital output is directly transferred to the operating control unit 122. Therefore, based on the operating principles described above, the control device 12 has been busy on sending capacitive load parameters to and receiving data from the analog to digital converter 120, and could consume electric power unnecessarily, such that the standby time of the touch panel device cannot be reasonably extended, and user's convenience cannot be improved, either.